Drive arrangement for timekeeping system

ABSTRACT

AN IMPROVED DRIVE ARRANGEMENT FOR A TIMEKEEPING SYSTEM. THE DRIVE ARRANGEMENT INCLUDES AN ELECTROSTATIC MOTOR INCLUDING A ROTOR HAVING A DIELECTRIC CIRCUMFERENTIAL SURFACE AND A PAIR OF ELECTRODES OPERATIVELY ASSOCIATED WITH THE ROTOR FOR DRIVING THE VOTOR IN RESPONSE TO D-C POTENTIAL APPLIED ACROSS SAID ELECTRODES. A NUCLEAR BATTERY IS CONNECTED TO SAID ELECTRODES FOR APPLYING A D-C POTENTIAL ACROSS SAID ELECTRODES TO DRIVE SAID ROTOR. THE TORQUE GENERATED BY THE ROTOR IS UTILIZED TO DRIVE A CONVENTIONAL MECHANICAL TIME INDICATING MEANS.

Oct. 5, 1971 EMERSON EI'AL 3,609,951

DRIVE ARRANGEMENT FOR TIMEKEEPING SYSTEM Filed March 27. 1969 m 46 FHE 4 TIMEKEEPING M AND \ND\CAT\NG MECHANLSM KMWENTORS mmm W; Enenson Lmmm l GosLmG United States Patent C 3,609,957 DRIVE ARRANGEMENT FOR TIMEKEEPING SYSTEM Frank W. Emerson and Lincoln J. Gosling, Peterborough,

Ontario, Canada, assignors to General Time Corporation, Stamford, Conn.

Filed Mar. 27, 1969, Ser. No. 811,115 Int. Cl. G04c 3/00 US. Cl. 5823 8 Claims ABSTRACT OF THE DISCLOSURE An improved drive arrangement for a timekeeping system. The drive arrangement includes an electrostatic mot'or including a rotor having a dielectric circumferential surface and a pair of electrodes operatively associated with the rotor for driving the rotor in response to DC potential applied across said electrodes. A nuclear battery is connected to said electrodes for applying a D-C potential across said electrodes to drive said rotor. The torque generated by the rotor is utilized to drive a conventional mechanical time indicating means.

The present invention relates generally to timekeeping systems and, more particularly, to an improved drive arrangement for timekeeping systems.

It is a primary object of the present invention to provide an improved drive arrangement for a timekeeping system which can be operated for a number of years with a single self-contained power source.

It is another object of the invention to provide an improved drive arrangement of the type described above which can be made with only a single moving part.

A further object of the invention is to provide an improved drive arrangement of the foregoing type which produces an output suitable for application to conventional mechanical timing trains for driving conventional indicating elements.

Yet another object of the invention is to provide such an improved drive arrangement which can be powered by a high voltage, low current power source.

A still further object of the invention is to provide such an improved drive arrangement which can be efiiciently manufactured at a low cost.

Other objects and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings, in which:

FIG. 1 is a schematic side elevation of a drive arrangement embodying the invention, with the power source shown in section;

FIG. 2 is a schematic end elevation of the drive arrangement shown in FIG. 1;

FIG. 3 is a schematic perspective of the electrode-rotor subassembly in the drive arrangement of FIGS. 1 and 2, and illustrating the electric field between the two electrodes;

FIG. 4 is a perspective view of a drive arrangement embodying the invention; and

FIG. 5 is a vertical section taken along line 55 in FIG. 4.

While the invention is susceptible of various modifications and alternative forms, certain specific embodiments thereof have been shown by way of example in the drawings which will be described in detail herein. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed but, on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Turning now to the drawings, there is shown a rotor fixed to a shaft 12 which also carries a pinion 11 to be 'ice rotated in response to rotation of the rotor 10. As the pinion 11 is rotated, it drives a gear 13 connected to a conventional timekeeping and indicating mechanism. That is, the pinion 11 and the :gear 13 serve to apply the torque generated by the rotor 10 to a conventional timekeeping and indicating mechanism.

In accordance with the present invention, at least the surface of the rotor 10 is made of a dielectric material operatively associated with a pair of circumferentially spaced electrodes, and a beta primary battery is connected to the electrodes for applying a D-C potential across the electrodes to drive the rotor. Thus, in the illustrative embodiment shown in the drawings, the rotor 10 is molded from a dielectric material, i.e., a material which will support an electric charge without conducting current. A pair of tapered electrodes 14 and 15 are mounted close to the outer circumferential surface 10a of the dielectric rotor 10, and are connected to the positive and negative terminals 17 and 16, respectively, of a source 18 of relatively high D-C voltage. When this voltage is applied across the two electrodes, ionized gas is produced and the dielectric rotor 10 rotates in the direction indicated by the arrows in FIGS. 1 and 3.

While it is not intended to limit the present invention to any particular theory, it is believed that the relatively high voltage applied to the electrodes 14 and 15 causes gas atoms in the vicinity of the electrodes 14 and 15 to be ionized thereby producing gas ions in the space adjacent the electrodes 14 and 15. These ionized clouds cause three effects: First, since the adjacent surface 10a of the rotor 10 is a dielectric, a charge is collected and retained on the rotor surface 10a; because the complementary electrode is of the opposite polarity, there is an attractive force between the rotor charges and the said complementary electrode, which causes rotation of the dielectric rotor 10. Secondly, the velocity of the ionized cloud caused by the point discharge of electrodes 14 and 15 produces an effect known as ion wind; this wind impinging on the rotor surface 10a causes torque to be transmitted to the rotor shaft 12.. The third effect of the ionized clouds is to polarize the dielectric material. The dielectric dipole moments may also contribute to the developed rotor torque.

Regardless of Whether the particular theory advanced above is a precisely accurate explanation of the observed phenomenon, it has been repeatedly demonstrated that the dielectric rotor 10 does, in fact, rotate in the direction indicated when a relatively high D-C potential (on the order of 6,000 volts, for example) is applied across a pair of electrodes located close to the rotor surface and circumferentially spaced therealong. Moreover, it has been found that such a system is capable of generating a torque sufficient to drive a conventional mechanical timekeeping and indicating system when the electrodes are connected to currently available D-C voltage sources. Specific working examples of such a drive system will be described in more detail below. It should be noted that the magnitude of output torque generated by any particular system embodying this invention is dependent upon a number of interdependent variables, such as the size of the rotor, the electrode spacing both with respect to each other and the dielectric rotor surface, the magnitude of the potential applied across the electrodes, the particular ionizable gas surrounding the electrodes and the dielectric rotor surface, the electrode material, the electrode shape, the dielectric material, the pressure of the ionizable gas, the temperature of the electrodes and the surrounding gas, and the like.

In accordance with one particular aspect of the invention, the electrodes are mounted so that the axes thereof are substantially tangential to the dielectric surface of the rotor. Thus, in the illustrative embodiment, the electrodes 14 and 15 are mounted so that the projected axes of the two electrodes are tangent to the circumferential dielectric surface of the rotor on diametrically opposite sides thereof. It has been found that this particular orientation of the electrodes relative to the rotor provides reliable rotor movement in a preselected direction, e.g., in the direction indicated by the arrows in FIGS. 1 and 3 in the illustrative arrangement.

In keeping with the invention, the source of the D-C potential applied across the electrodes 14 and 15 is a beta primary battery. Thus, in the particular embodiment illustrated in the drawings, the source 18 comprises a casing 19 forming a vacuum chamber containing an internal emitter 20 and an internal collector 21. The surface of the emitter 20 facing the collector 21 is coated with a radioactive material so as to generate a D-C potential across the two external terminals 16 and 17 connected to the collector 21 and the emitter 20, respectively. Beta primary batteries of the type illustrated are well known per se, and thus the illustrative source 18 will not be described in detail herein. Briefly summarized, the radioactive material on the emitter 20 emits radiation such as beta particles which are collected on the collector 21, leaving the emitter plate with a positive charge relative to the collector 21. Since the beta particles expend kinetic energy against the electrostatic field which exists between the cathode and anode, potential energy on the order of several thousand volts is developed at the external terminals. Although beta primary batteries of this type have been known per se, the relatively low power available from such sources has tended to limit the practical application thereof. One of the significant advantages of the present invention is that the electrostatic motor utilizes the high voltage, low current output from the nuclear battery to provide an output torque suitable for driving a conventional mechanical timekeeping and indicating mechanism.

In accordance with a further aspect of the present invention, an escapement mechanism is operatively connected to the rotor via spring means which store energy generated by continuous rotation of the rotor and intermittently drive the escapement mechanism. Thus, in the particular embodiment illustrated in FIGS. 4 and 5, the rotor shaft 12 is connected to an escape wheel associated with a pallet 31 mounted for oscillatory movement about a pallet staff 32. As will be apparent to those familiar with this art, the escapement mechanism is conventional per se, and includes a balance wheel 33 and a balance spring 34 operatively connected to the pallets 31 via a lever 35,. The spring mass system formed by the balance wheel 33 and the balance spring 34 tends to oscillate at a constant frequency in response to driving impulses applied thereto by the escape wheel 30 as it is driven by the shaft 12. As successive driving impulses are applied to the spring-mass system via the pallets 31, the pallets 31 are oscillated about the pallet staff 32 so as to permit only intermittent rotation of the escape wheel 30, thereby synchronizing the speed of rotation of the escape wheel 30 with the oscillatory frequency of the spring-mass system formed by the balance 33 and the balance spring 34.

To couple the intermittently rotating escape wheel 30 to the continuously rotating rotor 10 rigidly mounted on shaft 49, the rotor 10 is connected via post to one end of a spring 41 having its other end secured to the shaft 12a. Thus, the energy generated by continuous rotation of the rotor 10 is stored in the spring 41, and intermittently applied via the shaft 12 to the escape wheel 30 during the successive intervals when the escape wheel is released by the oscillating pallets 31.

To permit the spring 41 and the escape wheel 30 to be mounted on opposite sides of the rotor 10 a coupling means interconnects the spring 41 and the escape wheel 30 through the rotor, and the coupling means and the rotor are designed to permit rotational movement of rotor relative to the coupling means. Thus, in the illustrative embodiment of FIGS. 4 and 5, the inner end of the spring 41 is fastened to the shaft 12a by means of a collet 42. Also secured to the shafts 12 and 12a on opposite sides of the rotor 10, are a pair of cross arms 43 and 44 which link a pair of spaced rods 45 and 46 extending through the rotor 10. Since the shaft 12 rotates only intermittently, during the intervals when the escape wheel is released by the pallet 31, the rods 45 and 46 also rotate only intermittently. Accordingly, to permit continuous rotation of the rotor 10, the rods 45 and 46 are passed through a pair of arcuate slots 47 and 48 formed in the central portion of the rotor. Thus, during the intervals when the escape wheel 30 is stationary, the rotor 10 continues to rotate so that the trailing edges of the slots 47 and 48 approach the rods 45 and 46, respectively. Then when the escape wheel 30 is released to rotate the shafts 12 and 12a and the rods 45 and 46, the rods advance toward the leading edges of the slots 47 and 48. Consequently, it can be seen that the intermittent movement of the shaft 12 and the rods 45 and 46 does not interfere with the continuous rotation of the rotor 10.

In one working example of the arrangement shown in FIGS. 4 and 5, a rotor in diameter, and having an axially extending peripheral flange A" in length, was made of polyvinylacetal ((Delrin), which is dielectric material. The rotor weighed 250 milligrams. This rotor was secured to the escape wheel of a conventional mechanical clock movement of the type used in the commercially available Ships Bell clock made by Seth Thomas, division of General Time Corporation. A pair of electrodes were made by forming 0.2-inch long cones on the ends of two cylindrical rods As-inch in diameter and made of high carbon steel. These electrodes were mounted on diametrically opposite sides of the rotor, with the axes of the conical electrodes extending tangentially to the outer periphery of the disc, and with the tips of the electrodes spaced %4-lI1Ch from the circumferential surface of the dielectric rotor. With the entire assembly disposed in ambient air at room temperature, the output terminals of a constant current nuclear battery producing 5,000 volts D-C were connected to the two electrodes. The rotor rotated at a speed of 8 r.p.m., while driving the clock movement to which it was connected. The current flow in the electrode circuit was measured and found to be one nano ampere (l l0 which meant that the calculated power supplied by the drive arrangement was 5 microwatts (power=voltage current=5000 1 X 10- =5 X 10* watts=5 microwatts).

We claim as our invention:

1. An improved drive arrangement for a timekeeping system comprising the combination of an electrostatic motor including a rotor mounted for continuous rotation and having a dielectric circumferential surface and a pair of electrodes operatively associated with said dielectric surface of said rotor for driving said rotor in response to a D-C potential applied across said electrodes, said electrodes being angularly spaced apart around the dielectric circumferential surface of said rotor, a nuclear battery connected to said electrodes for applying a D-C potential across said electrodes to drive said rotor, and output means connected to rotor for applying the torque generated by said rotor to mechanical time indicating means.

2. An improved drive arrangement for a timekeeping system as set forth in claim 1 wherein said electrodes are elongated along axes which extend substantially tangential to the dielectric surface of said rotor.

3. An improved drive arrangement as set forth in claim 1 wherein said electrodes are mounted on diametrically opposite sides of said rotor in closely spaced relationship to said dielectric surface.

4. An improved drive arrangement as set forth in claim 1 wherein said electrodes are mounted in closely spaced relationship to said dielectric surface on said rotor.

5. An improved drive arrangement as set forth in claim 1 wherein said nuclear battery comprises means forming a vacuum chamber, and first and second internal electrodes spaced apart from each other within said vacuum chamber, one of said electrodes having a surface of radioactive material to generate a D-C potential, the other of said electrodes being provided for charge collection.

6. An improved drive arrangement as set forth in claim 1 wherein said nuclear battery is a beta primary battery.

7. An improved drive arrangement as set forth in claim 1 which includes an escapement mechanism operatively connected to said output means, and said output means includes spring means operatively connected to said rotor and said escapement mechanism for storing energy generated by continuous rotation of said rotor and intermittently driving said escapement mechanism.

8. An improved drive arrangement as set forth in claim 7 wherein said spring means is mounted on one side of said rotor and said escapement mechanism is mounted References Cited UNITED STATES PATENTS 2,835,105 5/1958- Favey 58-23 C RICHARD B. WILKINSON, Primary Examiner E. C. SIMMONS, Assistant Examiner U.S. O1. X.R. 310-3, 6 

